JP2591394Y2 - Integral type power steering device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an integral type power steering device.

[0002]

2. Description of the Related Art An integral type power steering device generally includes a cylinder formed in a gear housing and a piston which is slidably fitted in the cylinder to partition the cylinder into two pressure chambers. A rack formed on one side of the piston, a sector shaft arranged in a direction perpendicular to the direction in which the piston reciprocates, and connected to the steered wheels via a link mechanism, and a sector shaft integrated with the sector shaft. And a sector gear that meshes with the rack and rotates forward and reverse with the reciprocation of the piston.
By switching the control valve by operating the steering handle, hydraulic oil is supplied to one pressure chamber of the cylinder, discharged from the other pressure chamber and returned to the tank, and the piston is operated by the pressure difference between these two chambers. By doing so, an assisting force in the steering direction is applied.

[0003] In the integral type power steering device having the above-described structure, a backlash is required between the rack and the sector gear for smooth operation. The problem is that the play of the car increases and the vehicle fluctuates,
By moving the sector shaft in the axial direction by an adjusting screw mounted on the sector shaft, gear backlash is reduced to zero at a neutral position of the steering wheel, so that good steering stability can be obtained. However, in a normal case, the gear backlash increases due to a change over time, which causes play between the rack and the sector gear to increase the play of the steering wheel, thereby deteriorating the steering stability during high-speed running. Has a problem.

[0004] Therefore, an integral type power steering apparatus has been proposed in which the steering stability is improved by always reducing the gear backlash to zero or applying an appropriate preload. An example of such a conventional integral power steering apparatus will be described with reference to FIG. A piston 104 is slidably fitted in a cylinder portion 102 of the gear housing 100. A rack 106 is formed on a side surface of the piston 104. A sector shaft 108 is arranged in a direction orthogonal to the sliding direction of the piston 104, and a sector gear 110 provided on the sector shaft 108 meshes with the rack 106 of the piston 104. A through hole 112 is formed in a side wall surface of the gear housing 100, and a plunger 114 is slidably inserted into the hole 112, and a distal end 114a of the plunger 114 is moved into a cylinder by a spring 116 disposed inside the hole 112. It protrudes into 102. A notch 118 is formed on a side surface of the piston 104, and a tip 114 a of the plunger 114 is elastically contacted with the notch 118 to apply a rotational force to the piston 104 in the direction of arrow A. By applying a rotational force to the piston 104 in this manner, the rack 106 is moved to the sector gear 11.
The gear is always brought into contact with the small end 110a (right side in the figure) of zero so that the gear backlash is always zero or an appropriate preload is applied.

[0005]

In the conventional integral type power steering apparatus described above, a plunger for applying a rotational force to a piston and a spring for urging the plunger are provided inside the side wall of the gear housing. There is a drawback that the entire housing is enlarged, and a portion provided with the plunger and the spring is enlarged outward, which is not preferable in terms of the layout of the vehicle. In addition, there is a danger that external leakage may occur. Further, in the conventional integral type power steering device, the plunger is formed of a metal material, and there is a problem that the sliding resistance is large due to the metal sliding with the piston. As a result, the feeling of cutting becomes unclear and the steering wheel may be cut too much or not enough, and there is also a problem that the steering wheel is poorly returned, so that the steering wheel fails to return or is returned too much.

The present invention has been made to eliminate the above-mentioned disadvantages, and has a structure that does not increase the size of the power steering device as a whole, does not cause external leakage, and reduces a feeling of friction. By doing so, it is possible to provide an integral power steering device that can improve the steering stability during high-speed running and improve the return of the steering wheel.

[0007]

An integral type power steering apparatus according to the present invention is slidably fitted in a cylinder to partition the inside of the cylinder into two pressure chambers. And a sector gear that meshes with the rack and is rotated forward and backward with the reciprocation of the piston. A steering assist force is obtained by operating the piston by supplying and discharging the pressurized fluid.Furthermore, the piston has a eccentric direction on the back side of the portion where the rack is formed, with respect to the axis of the piston. A sliding hole is formed. A plunger is slidably fitted in the sliding hole, and a ball is rotatably held at the tip of the plunger. Te is obtained as by elastic contact ball by pressing the plunger into the inner wall of the cylinder, imparting a rotational force to the piston.

[0008]

[Function] In the integral type power steering device having the above configuration,
A plunger that rotatably holds a ball is provided at the tip inside the piston, the plunger is urged by a spring, and the inner wall of the cylinder is pressed through the ball, and the piston is rotated by the reaction force from the cylinder. By applying a force, the rack formed on the side surface of the piston can be pressed against the end of the sector gear to reduce gear backlash. In addition, there is no danger that the backlash increases due to a change with time, and that the steering stability at high speed is deteriorated.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the embodiments shown in the drawings. FIG. 1 is a longitudinal sectional view of an integral type power steering device according to an embodiment of the present invention. FIG. 2 is a sectional view taken along the line II-II of FIG. , The piston 6 is slidably fitted.
The inside of the cylinder 4 is divided into two pressure chambers 8 and 10 by the pressure. A rack 12 is formed on one side surface (the lower surface in FIGS. 1 and 2) of the piston 6, and a sector gear 14 integrally provided on a sector shaft 13 connected to a steering wheel (not shown) is provided on the rack 12. Are reciprocated with the reciprocal movement of the piston 6. The teeth of the sector gear 14 are inclined in the axial direction of the sector shaft 13 as shown in FIG.
By moving the sector shaft 13 in the axial direction by the adjusting screw 15 provided at the end of the sector shaft 13, the meshing state with the rack 12 is adjusted, and the backlash between the two 12 and 14 is eliminated.
Alternatively, an appropriate preload can be given.

A ball screw groove 18 is screwed into a hole 16 in the shaft core of the piston 6, and the worm shaft 2 is provided through a number of balls 20 accommodated in the ball screw groove 18.
2 is screwed. A valve housing 24 is fixed to one end (the right side in FIG. 1) of the gear housing 2, and a stub shaft (input shaft) 26 is disposed in the valve housing 24 so that the worm shaft 22 is aligned with the worm shaft 22. I have. Stub shaft 2 of worm shaft 22
A large-diameter cylindrical portion 22a is formed on the side of the cylindrical portion 22.
The end of a stub shaft 26 is fitted in 2a, and these two shafts 22, 26 are connected by a torsion bar 28 inserted into a hole of each shaft core.
The stub shaft 26 is rotated by operating a steering handle (not shown).

Inside the valve housing 24, an inner valve 30 fitted around a stub shaft 26 and connected by a pin 27 to rotate integrally with the stub shaft 26, and an enlarged cylinder at the end of the worm shaft 22 A control valve 34 of a rotary type, which is formed in the shape portion 22a and includes an outer valve 32 fitted on the outer periphery of the inner valve 30, is housed.

Since the configuration of the control valve 34 is well known in the art, its detailed description is omitted. However, the control valve 34 communicates with an oil pump (not shown) via a supply passage, and communicates with a tank (not shown) via a return passage. When the control valve 34 is switched by operating the steering handle, the pressure fluid discharged from the oil pump is supplied to one of the pressure chambers 8 and 10, and the other pressure chamber is communicated with the tank. A pressure difference is generated between the two chambers, and the piston 6 is operated by the pressure difference to apply an assisting force in the steering direction.

An urging means 36 is provided inside the piston 6 for pressing the inner wall surface of the cylinder 4 and applying a rotational force to the piston 6 by the reaction force. The structure of the urging means 36 will be described with reference to FIGS. 1 and 2 and FIGS. A through hole 40 is formed along the axial direction of the piston 6 on the rear side of the portion of the piston 6 where the rack 12 is formed (the lower surface side in FIGS. 1 and 2). Further, a circular hole 42 penetrating a wall surface near the outer peripheral surface of the axial through hole 40 is provided. A line O ₁ passing through the center of the circular hole 42 (see FIG. 2) is connected to the center of the worm shaft 22 (the piston 6).
With respect to the rotation center O ₂ ) of the sector gear 14,
4a. In the circular hole 42, a plunger 44 is slidably fitted.
It is pressed from the inner side by a leaf spring 46 arranged in the inner side.

A spherical hole 44a is provided at the tip of the plunger 44.
Are formed in the spherical hole 44a.
Are housed and rotatably held. Further, a slit 44b crossing both side surfaces is formed on an inner side of a tip portion which rotatably holds the ball 45, and a concave portion 44c is formed at a central portion of the slit 44b. (See FIG. 5). A holder 50 having a substantially semicircular cross section is arranged in a hole 40 passing through the piston 6 in the axial direction, and holds the leaf spring 46. The leaf spring 46 has a central portion 46a which is curved and protrudes.
a is fitted into the concave portion 44 c of the plunger 44 and presses the plunger 44 outward of the piston 6. A shallow groove 50a for holding the leaf spring 46 is formed on the upper surface of the holder 50, and horizontal portions 46b and 46c at both ends of the leaf spring 46 are arranged in the groove 50a. At one end (left side in FIG. 3) of the hole 40 penetrating the piston 6 in the axial direction, a step portion 40a is formed, which serves as a stopper when the holder 50 moves leftward in FIG. Conversely, in the right direction, the left engaging step 50b of the shallow groove 50a of the holder 50 functions as a stopper. A flange 44d is provided at an end of the plunger 44 inserted inside the circular hole 42.
The flange portion 44d is engaged with the inner surface of the axial through hole 40 provided at the back of the circular hole 42 so as not to protrude from the circular hole 42. The plunger 44 and the holder 50 are both made of a material such as resin.

On the other hand, when the plunger 44 moves along with the reciprocating motion of the piston 6, the inner wall of the cylinder 4 at the portion where the ball 45 held at the tip abuts extends in the axial direction of the cylinder 4. A recess 48 is formed. The bottom surface of the concave portion 48 (that is, the surface on which the ball 45 held at the tip of the plunger 44 abuts) is a flat surface perpendicular to the direction in which the plunger 44 slides.

In the integral type power steering apparatus according to the above configuration, the piston 6 is slidably fitted in the circular hole 42 of the piston 6, and is moved outward from the piston 6 by the leaf spring 46 from the inside of the hole 42. Plunger 44 biased toward
Presses the flat surface of the concave portion 48 formed on the inner wall of the cylinder 4 via the ball 45 held at the tip end thereof, in the direction in which the plunger 44 presses the wall surface of the cylinder 4, that is, Since the direction in which the plunger 44 slides in the circular hole 42 is deviated from the line passing through the axis O ₂ of the piston 6, the reaction force from the cylinder 4 (the direction of the arrow B in FIG. 2) To apply a rotational force in the direction of arrow C. As a result, the rack 12 formed on the piston 6 is pressed against the small end 14 a of the sector gear 14,
Gear backlash between the rack 12 and the sector gear 14 can always be zero. This power steering device,
Even if the backlash increases due to wear due to use, the backlash is always applied to the piston 6 by the urging means 36 in the rotational direction (C direction). It is possible to maintain good steering stability during high-speed running without increasing.

FIG. 6 is a graph showing the relationship between the rotation angle of the worm shaft 22 and the rotation angle of the sector shaft 13. When there is no backlash and when there is a backlash, they are indicated by a dashed line a and a broken line b, respectively. However, in the case of this embodiment, the piston 6 is rotated to keep the rack 12 and the sector gear 14 in contact with each other even when the backlash occurs due to wear due to use or the like as shown by the solid line c in the present embodiment. Since it adjusts to the meshing state,
The sector shaft 13 is rotated at the same time as the worm shaft 22 is rotated, so that play does not occur in the worm shaft 22, and good and safe actual vehicle performance can be obtained especially during high-speed running.

A spherical hole 44a is formed at the tip of the plunger 44, and a ball 45 is rotatably held in the hole 44a. Since the ball 45 is rolled, it is possible to eliminate the frictional feeling of the conventional integral type power steering device, to improve the steering stability at high speed running, and to return the steering wheel. Can be better. In the above embodiment, the rack 12
Is applied to the piston so that the piston 6 is pressed against the small end portion 14a (right side in FIG. 2) of the sector gear 14, but the piston 6 is moved counterclockwise in FIG. By rotating the rack, the rack 12 of the piston 6 may be pressed against the large end 14 b of the sector gear 14. Further, the plunger 44 does not need to be in sliding contact with the entire inner surface of the circular hole 42. For example, both side surfaces of the cylindrical plunger 44 may be cut, and this portion may be a flat surface that does not slide on the inner surface of the hole 42. . Furthermore, the hole 42 into which the plunger 44 slides and the through hole 40 in the axial direction in which the leaf spring 46 and the holder 50 are housed need not necessarily be circular, and may have other shapes such as a square cross section. Good.

FIGS. 7 to 9 show a second embodiment, in which a plunger 44, a ball 45, a leaf spring 46 and a holder 50 have the same shapes as in the first embodiment.
The configuration of the hole 42 into which the plunger 44 is inserted and slides is the same, but the configuration of the hole 140 in which the leaf spring 46 and the holder 50 are accommodated is different. That is, the hole in which the holder 50 is housed is the hole 40 that penetrates the piston 6 in the axial direction in the above embodiment, but in this embodiment,
In a direction orthogonal to the axis O ₂ of the piston 6 (see FIG. 2),
In addition, there is a lateral hole 140 that does not cross the axis O ₂ (does not pass through the axis). Also in this embodiment, a ball 45 rotatably held at the tip of a plunger 44 urged by a leaf spring 46 engages a concave portion 48 having a flat bottom surface provided on the inner wall of the cylinder 4 so as to engage the cylinder. 4
And a rotational force is applied to the piston 6 by the reaction force from the cylinder 4, so that the rack 12 and the sector gear 1
4 is always kept free of gear backlash,
Good steering stability can be ensured. The plunger 44 may have a cylindrical shape, or may have a flat surface by cutting both sides 144a and 144b of the cylinder 144 as shown in FIG.

FIG. 10 shows a third embodiment.
In this embodiment, a coil spring 246 is used instead of the leaf spring 46 used in each of the above embodiments. The piston 6 is formed with a circular hole 42 into which the plunger 244 is fitted and slides, and a through hole 40 communicating with the inside of the circular hole 42 and extending in the axial direction of the piston 6. A circular hole 244 b is provided inside the plunger 244, and a coil spring 246 is housed in the hole 244 b to urge the plunger 244 toward the inner wall of the cylinder 4. A spherical hole 244a is provided at the tip of the plunger 244.
Is formed, and the ball 245 is housed in the hole 244a and is rotatably held. In the through hole 40 extending in the axial direction of the piston 6, a holder 250 for holding the coil spring 246 is arranged. This holder 25
Both the plunger 0 and the plunger 244 are made of resin, as in the above embodiment. The urging means 236 in the above configuration
The assembling procedure is as follows.
0 is inserted, and then the coil spring 246 and the plunger 244 are sequentially inserted. In this example,
As in the above embodiments, a rotational force is applied to the piston 6, and the rack 12 of the piston 6 is pressed against the sector gear 14 to eliminate gear backlash between the two.
Similar effects can be obtained.

In the first to third embodiments, the structure of the piston 6, the plungers 44 and 244, the balls 45 and 245, and the springs 46 and 246 is changed. 245
The shape of the concave portion 48 of the cylinder 4 with which
As shown in FIG. 11, the piston 6 had the same flat surface over the entire stroke range S. Note that FIG. 11 and FIGS. 13 to 15 described below correspond to the XI of FIG.
It is sectional drawing which follows the -XI line. As shown in these figures, various characteristics can be obtained by changing the shape of the cylinder 4 side. For example, in a region R where it is necessary to improve the return of the handle as shown in FIGS.
By forming a tapered surface 148a on the bottom surface of the concave portion 148 of the cylinder 4 or forming a deep flat surface 248b in the middle between the tapered surface 248a and the tapered surface 248a, the pressing force by the plunger 44 is reduced and the return is improved. On both sides of the region R, the rack 12 formed on the piston 6 and the sector gear 14 are strongly engaged when the handle is cut.

As shown in FIG. 15, the shape of the concave portion 348 of the cylinder 4 in the stroke range S of the piston 6 is such that the rectilinear region 348a including the central rectilinear position is deep, and both sides thereof are tapered portions 348b. Thus, the pressing force of the plunger 44 is reduced in the return stroke of the piston 6 to improve the return of the handle, and the shallow portions 348c are provided on both sides of the tapered portion 348b so that the rack 12 and the sector gear 14 of the piston 6 are connected. Be able to engage more strongly. The deepest recess 348d is formed at both ends of the stroke range S of the piston, which is an area where preloading is unnecessary. In this deepest recess 348d, the plunger 44 is pushed outward by a spring (not shown), and a stopper (flange) formed on the inner side
When stopped by 44d, the ball 45 held at the tip of the plunger 44 does not come into contact with the bottom surface of the concave portion 348 of the cylinder 4 so as to have a gap δ. The preload can be released in the region 348d where the ball 45 held by the plunger 44 is not brought into contact with the cylinder 4 as described above.

Furthermore, Figure 17 shows another embodiment, in this embodiment, the piston 6, and a plane perpendicular to the axis O _2, circular does not pass through the axis O ₂ slide hole 442 A coil spring 446 is arranged inside the sliding hole 442 to urge the plunger 444 inserted into the opening side of the sliding hole 442 outward. A sleeve 451 is screwed and fixed to the opening side of the sliding hole 442, and a small-diameter portion at the distal end of the plunger 444 passes through the inside of the sleeve 451. A flange 444 a is formed at an inner end of the plunger 444 so that the sleeve 4
By engaging with the inner side end surface of 51, it does not fall off. The sleeve 451 may be fixed by press fitting or the like. A notch (a tool groove for screwing) 451a is formed on the outer end surface of the sleeve 451 (see FIG. 18), and the inner surface on which the plunger 444 slides is provided with a pressure fluid that penetrates both end surfaces. An escape groove 451b is formed. On the other hand, the inner surface of the cylinder 4 is formed with a concave portion 448 similar to the above embodiments, and a ball 445 rotatably held at the tip of the plunger 444 elastically contacts. In this embodiment, the same effects as those of the above-described embodiments can be obtained.
By means of 1, the plunger 444 can be stably held and the slidability can be improved.

FIG. 19 shows still another embodiment.
In this embodiment, the sliding hole 542 of the piston 6 is
The rack 12 has a large diameter, the other end has a small diameter, and a step 542a is provided therebetween. And
From the opening of the sliding hole 542 on the rack 12 side, the flange 551
By inserting a sleeve 551 having a “a” and inserting a plug 553 having a cylindrical portion 553a from the outside thereof and screwing the same, the flange 551a of the sleeve 551 is engaged with the step 542a of the sliding hole 542. I have to stop. In addition, 551c is a tool hole at the time of plug screwing. A coil spring 5 is provided in the cylindrical portion 553a of the plug 553.
46 are housed therein and urge the plunger 544 inserted through the inside of the sleeve 551 outward. A flange 544a is also formed at the inner end of the plunger 544,
The flange 551a of the sleeve 551 prevents the sleeve 551 from falling off. An escape groove 551b for the pressure fluid similar to that of the above embodiment is also formed on the inner surface of the sleeve 551. This embodiment can achieve the same operation and effect as the above embodiment.

[0025]

As described above, according to the present invention, a sliding hole is formed inside a piston, and a plunger holding a ball rotatably at its tip is slidably housed and disposed inside. The above-mentioned ball is pressed against the inner wall of the cylinder by applying a force to the piston to apply a rotational force to the piston by the action of the reaction force from the cylinder. The steering wheel can be engaged in a state where the steering wheel does not move, and the steering stability during high-speed running can be improved, and the return of the steering wheel can be improved. In addition, through holes in the gear housing
Is not formed, so external leakage may occur.
Absent.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an integral type power steering device according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a longitudinal sectional view of a main part (biasing means) of the embodiment.

FIG. 4 is a cross-sectional view of a main part (biasing means) of the embodiment.

FIG. 5 is a vertical sectional view of a plunger constituting the urging means.

FIG. 6 is a graph showing a relationship between a rotation angle of a worm shaft and a rotation angle of a sector shaft in the integral power steering apparatus according to the embodiment.

FIG. 7 is a cross-sectional view of a main part (biasing means) of the second embodiment.

FIG. 8 is a longitudinal sectional view of a main part (biasing means) of the second embodiment.

FIG. 9 is a plan view of a plunger constituting the urging means of the second embodiment.

FIG. 10 is a longitudinal sectional view of a main part (biasing means) of a third embodiment.

11 is a longitudinal sectional view showing an example of a concave portion of the piston and taken along a line XI-XI in FIG. 12;

FIG. 12 is a cross-sectional view illustrating a shape of a concave portion of a piston.

FIG. 13 is a longitudinal sectional view showing an example of a concave portion of a piston.

FIG. 14 is a longitudinal sectional view showing another example of the concave portion of the piston.

FIG. 15 is a longitudinal sectional view showing another example of the concave portion of the piston.

FIG. 16 is a view corresponding to FIG. 2 of a mechanism for eliminating backlash of a conventional integral power steering device.

FIG. 17 is a sectional view showing a main part of another embodiment.

18 is a view in the direction of the arrow XVIII in FIG. 17;

FIG. 19 is a cross-sectional view showing a main part of another embodiment.

[Explanation of symbols]

 Reference Signs List 4 cylinder 6 piston 8 cylinder pressure chamber 10 cylinder pressure chamber 12 rack 14 sector gear 34 control valve 36 biasing means 42 sliding hole 44 plunger 45 ball 48 cylinder inner wall (bottom of cylinder recess)

Claims (4)

(57) [Scope of request for utility model registration] A piston is slidably fitted in a cylinder to partition the inside of the cylinder into two pressure chambers, a rack formed on a side surface of the piston, and meshed with the rack to form a piston. An integral type power steering device comprising: a sector gear that is rotated forward and backward with reciprocation, and switches a control valve by operating a steering handle to supply and discharge pressure fluid to both pressure chambers.
A sliding hole is formed on the back side of the portion where the rack is formed, facing a direction eccentric to the axis of the piston. A plunger is slidably fitted in the sliding hole. The ball is rotatably held at the tip of the cylinder, and the plunger is pressed by a spring disposed inside the sliding hole to elastically contact the ball with the inner wall of the cylinder, thereby applying a rotational force to the piston. Integral type power steering device. 2. A hole in a direction perpendicular to a sliding hole in which the plunger is fitted is provided inside the piston, and a leaf spring held by a holder is accommodated in the hole perpendicular to the sliding hole. The integral type power steering device according to claim 1, wherein the plunger is biased toward the cylinder. 3. The integral type power steering device according to claim 2, wherein the holder is provided with an engagement projection for preventing the leaf spring from falling off. 4. A plunger is formed at an inner side end of the plunger, and the flange is engaged with an inner surface of the orthogonal hole to prevent the plunger from being pulled out of the sliding hole. 2. The integral type power steering device according to 1.